Electrical contact coupling for liquid cooled cable



April 1 1951 L. H. TIMMINS 2,549,264

ELECTRICAL CONTACT COUPLING FOR LIQUID COOLED CABLE Filed Nov. 1, 1947 NVENTOR L 50 H. Tuw/vmvs Patented Apr. 17, 1951 ELECTRICAL CONTACT COUPLING FOR LIQUID COOLED CABLE Leo H. Timmins, Montreal, Quebec, Canada, assignor to Chromium Mining and Smelting Corporation, Ltd., Sault Ste. Marie, Ontario, Canada, a corporation of Ontario Application November 1, 1947, Serial No. 783,472

7 Claims.

This invention relates to electrical contact couplings and, more particularly to electrical contact couplings for liquid-cooled flexible conductors. An object of the invention is the provision of a compact electrical contact coupling characterized by low electrical contact resistance for connecting flexible liquid-cooled conductors to relatively inflexible liquid-cooled conductors for use in electric furnace operation, and the like.

In the operation of many types of electric furnaces it is necessary to supply electric current tothe furnaces through flexible conductors capable of carrying currents of high amperage. Such flexible conductors are required, for example, in the operation of submerged are electric furnaces, during operation of which the electrodes are moved vertically within the furnace, and in the operation of tilting electric furnaces of various types. Because of the high currents which such conductors must carry, and because of the proximity of some parts of the conductors to the furnace itself, liquid cooling means are employed to maintain the conductors at proper and safe operating temperatures. Power supply bus conductors are cooled in conventional practice by using hollow conductors through which a cooling liquid such as water is forced. Flexible conductors, on the other hand, are generally stranded wire cables and are cooled by an outer flexible cooling jacket permitting the flow of Water over the surface of the cable. A suitable compact contact coupling for connecting such a hollow bus conductor with an externa ly cooled flexible cable presents a problem not only in providing a water-tight joint which may be readily connected or disconnected but such a coupling should be characterized by low electrical contact resistance because of the large currents flowing through the conductors. The flow of large currents through a contact having any appreciable electrical resistance generates such a quantity of heat as to cause not only local overheating of the contact coupling but also oxidation of the surfaces of the metal in contact with one another with resulting further increase in its electrical contact resistance.

I have now devised an electrical contact coupling for connecting a hollow liquid-cooled conductor to a flexible liquid-cooled conductor which is superior to such couplings proposed or used heretofore. The electrical contact coupling of my invention is compact and permits ready connection or disconnection of such conductors. The electrical contact coupling of my invention further provides a liquid-tight connection beliquid-cooled conductor having an outer flexible" cooling jacket in accordance with my invention comprises a coupling member and means for holding the end of the hollow conductor in firm contact with the coupling member in such man ner as to provide substantially liquid-tight communication between the hollow conductor and the coupling member. ventionthe coupling member, which is advantageously substantially cy indrical, is provided with a tapered internal opening adjacent one end portion thereof adapted to engage with a tapered end of the hollow conductor.

ternal opening of the coupling member. Means are also provided for securing a flexible con ductor and its outer cooling jacket to the coupling member in such manner as to provide substantial y liquid-tightcommunication between the coupling memberand the cooling jacket'of the flexible conductor.

ible conductor is connected to the coupling member by means of a spline member secured to the end of the flexible conductor, the spline member being further secured within an internal opening inthe coupling member adjacent the other end thereof from the tapered internal opening of the coupling member. The spline member comprises a cylindrical body portion'adapted to fit over the end of the flexible conductor and is provided with a plurality of coaxially disposed projections spaced radially about one end of the body portion. The outer flexible jacket about the flexible conductor is secured to the outer surface of the body portion of the spline member, and

openings extending longitudinally of the axis oi" the spline member provide communication be tween the interior of the coupling member and} the cooling jacket of the flexible conductor;

These openings permitting flow of the cooling liquid through the spline member preferably extend longitudinally of the axis of the spline mem-' ber through both the body portion and the projections of the spline member.

These and other details of electrical contact couplings in accordance with 'my invention will In' accordance with my in-' 7 Means are provided for holding the tapered end of the hollow conductor in firm contact within the tapered in- In accordance with the now' preferred embodiment of my invention the flex-' be further understood by reference to the accompanying drawings in which:

Fig. 1 is a view in cross-section showing the end portion of a hollow liquid cooled conductor provided with a tapered end;

Fig. 2 shows an annular split ring or key for attachment to the hollow conductor shown in Fig. 1;

Fig. 3 is a view in cross-section of the coupling member of the invention;

Fig. 4 is a view in cross-section of a clamping nut for holding the tapered end of the hollow conductor within one end of the coupling member shown in Fig. 3;

Fig. 5 is a side view of the spline member of the invention;

Fig. 6 is an end view of the spline member shown in Fig. 5;

Fig. 7 is a view partly in cross-section showing a hollow liquid-cooled conductor connected to a flexible liquid-cooled conductor by means of the electrical contact coupling of the invention; and

Fig. 8 is a view taken along line 8-8 in Fig. '7.

The end of a water-cooled hollow conductor ill to be connected with a flexible conductor by means of the electrical contact coupling of the invention is provided with a tapered end H as shown in Fig. 1, the taper being such that the portion of the conductor having the smallest external diameter is adjacent the end of the conductor. The conductor is further provided with two annular recesses l2 and I3 cut into the outer surface of the conductor a short distance inwardly from the beginning of the taper. The annular ring it shown in Fig. 2 is split to form two separate halves which together form an annular ring having an internal diameter substantially the same as the diameter of the annular recesses 42 and i3 and having an outer diameter somewhat greater than the external diameter of the conductor H1. The split ring is thus adapted to be placed in the annular recess l2 so as to form a key engaging the conductor in.

The coupling member l5 shown in Fig. 3 is substantially cylindrical in shape. The coupling member has an internal opening IS in one end thereof provided with a tapered surface corresponding substantially to the taper of the tapered end H of the conductor H). The outer surface of this same end of the coupling member I5 is provided with the threads H. The other end of the coupling member is provided with an internal opening [8 having a substantially uniform internal diameter slightly greater than the overall diameter of the cooling jacket of a flexible water-cooled conductor to which it is to be connected. The junction of the walls of the uniform diameter opening [8 and of the tapered opening iii of the coupling member forms an annular shoulder substantially intermediate the interior of the coupling member [5. A plurality of radially disposed openings 2| are provided in the portion of the coupling member having the uniform internal diameter, the openings being located longitudinally of the coupling member I5 in such manner that the end of the opening nearest the center of the coupling member is close to or in alignment with the shoulder 2a. The exterior surface of the coupling member the end pposite the threaded end of the coupling member is provided with a taper such that the thickness of the walls of the couplin member at the extremity 22 of this end i substantially reduced. The shape of the coupling member of my invention is such that it may readily be formed by casting, thus requiring only a minimum amount of machining and finishing.

The clamping nut shown in Fig. 4 comprises a body portion 23 provided at one end thereof with internal threads 24 adapted to engage the threads I! of the coupling member 15. The clamping nut is further provided within the interior of its other end with an annular shoulder 25 of such size that the internal diameter of the opening provided by the annular shoulder is at least as great as the outer diameter of the hollow tube ill. The annular shoulder 25 is preferably positioned a short distance inwardly from the end of the body portion 23, leaving the extremity of the body portion projecting outwardly to form the flange l9.

In connecting the coupling member IE to the end of the hollow conductor H], the clamping nut shown in Fig. 4 is slipped over the end of the hollow conductor [0 past the annular recess l2. The tapered end portion ll of the hollow oonductor is inserted within the tapered internal opening [6 of the coupling member. The split ring 14 is then placed in the annular recess 12 and the clamping nut is advanced toward the tapered end of the hollow conductor until the threads 24 of the clamping nut engage the threads ll of the coupling member. As the clamping nut is screwed onto the end of the coupling member the shoulder 2-5 approaches and engages the split ring [4 and forces the tapered end ll of the hollow conductor into firm contact with the walls of the tapered internal opening l6 of the coupling member, as shown in Fig. '7. The uniform and firm contact between the tapered portions of the conductor l0 and of the coupling member 15 provides an excellent electrical contact between these two elements.

The spline member shown in Figs. 5 and 6 comprises a cylindrical body portion 26 having an internal diameter such that it may be slipped over the end of a flexible cable such as the flex-- ible stranded cable 21 illustrated in Fig. 7. The

ible outer cooling jacket 28 of the flexible cable 27. The spline member further comprises a plurality of coaxially disposed projections 30 spaced radially about one end of the cylindrical body portion 26. The inner surfaces of the projections 39 are aligned with the internal surface of the cylindrical body portion 25. The thickness of the projections '30 is such that their outer curved surfaces 3| have a diameter approachingthe diameter of the internal opening l8 of the coupling member, and the area of the outer curved surface 3| of each projection is such as to substantially completely close each of the openings 2| in the side walls of the coupling member 15. In the electrical contact coupling illustrated in the drawings six such projections 30 are pro vided on the spline member and six correspondingly positioned openings 2| are provided in the coupling member I5. Each of the projections 30 is provided with an opening 32 extending therethrough longitudinally of the axis of the spline member and further extending through the cy-' lindrical body portion 26.

In connecting the flexible water-cooled con ductor to the coupling member I5, the spline member is first attached to the flexible conductor. This is done in accordance with my now preferred practice by first weldin or brazing is then slipped over the end of the flexible conductor 21 with the projections 30 extending toward the welded end of the flexible conductor as shown in Fig. 7. The spline member is secured about the end of the flexible conductor 21 by welding or brazing the edges of the projections 30 and the adjoining edge of the cylindrical body portion 26 to the surface of the flexible conductor 21, as indicated by the welding ridges 29 in Fig. 8. The end of the flexible water jacket 28 about the flexible conductor 21 is then secured to the outer surface of the cylindrical body portion 26 of the spline member, this being accomplished, for example, by welding or brazing, or the like. The end of the flexible water jacketed cable having the spline member secured thereto is inserted within the opening l8 of the coupling member I5 with the outer surfaces 3| of the projections 30 substantially closing the corresponding openings 2| in the coupling member. The outer surfaces 3| of the projections 30 are welded to the inner surface of the internal opening 18 of the coupling member, as shown by the P welding ridges 33 in Figs. '7 and 8, by access through the openings 2 I. I have found that low melting-point copper welding rods may be used with particular advantage in making the welded joints referred to hereinabove. A completely water-tight connection between the flexible water jacketed conductor and the coupling member I5 is provided by means of a wiped solder connection 34, or the like, sealing the joint between the flexible cooling jacket 28 and the reduced end portion 22 of the coupling member. The end of the coupling member l5 covering the end of the flexible conductor 21 and its flexible water jacket 28 holds this end of the water-cooled conductor immobile and thus protects the welded joints within the coupling member against failure which might otherwise occur due to flexing of the conductor and its cooling jacket within the coupling member.

It will be seen, therefore, that the electrical contact coupling of the invention provides excellent electrical connection between a hollow conductor and a flexible conductor by means of forced contact between the hollow conductor and the contact coupling and by means of welded joints between the contact coupling and the flexible conductor. The contact resistance of the coupling isso low that in actual use in the operation of a thru phase 5500 kva. submerged are electric furnace no measurable voltage drop through the entire coupling could be detected.

A water-cooled joint is also provided by the electrical contact coupling of my invention, the cooling water flowing through the interior of the hollow tube l into the interior of the coupling member l and thence through the openings 32 in the spline member into the interior of the flexible jacket 28 surrounding the flexible conductor 21. The electrical contact coupling of the invention is not only compact, durable and watertight, but the coupling welded to a flexible conductor may be readily connected to or disconnected from a hollow bus conductor. The simplicity of connecting the coupling to the hollow conductor I!) has been illustrated hereinabove. The coupling welded to the flexible conductor 21 may be readily disconnected from the hollow conductor Ill by inserting another split key such as the annular split ring 14 in the annular recess l3 of the hollow conductor and by unscrewing the clamping nut from the coupling member. As the clamping nut is thus unscrewed the shoulder 25 and the flange [9 of the clamping nut approaches and engages the split ring H in the annular recess l3 and forces the tapered end ll of the hollow conductor l0 out of the tapered open- .ing l6 of the coupling member.

I claim:

1. In an electrical contact coupling for connecting a hollow liquid-cooled conductor to a flexible conductor having an outer flexible cooling jacket, comprising a coupling member having an opening in one end portion thereof adapted to engage with an end of the hollow conductor, means for holding the end of the hollow-coniductor in firm contact within the opening of the coupling member, and means for securing an end of the flexible conductor and its outer flexible cooling jacket within the other end portion of the coupling member the improvements that comprise an annular element within said coupling provided with a plurality of longitudinally ex- .tending openings permitting passage of the cool ing medium between the interior of the cooling jacket of the flexible conductor and the interior of the hollow conductor.

2. An electrical contact coupling for connectin a hollow liquid-cooled conductor to a flexible liquid-cooled conductor having an outer flexible cooling jacket, comprising a coupling member having a tapered opening in one end portion thereof adapted to engage with a tapered end of .the hollow conductor, means for holding the tapered end of the hollow conductor in firm contact within the tapered opening of the coupling member, and a spline member secured to the end of .the flexible conductor, provided with axially extending openings providing communication for the cooling liquid between the interior of the cooling jacket of the flexible conductor and the interior of the hollow conductor, the spline member being secured within an internal opening in the coupling member adjacent the other end thereof.

3. An electrical contact coupling for connectin a hollow liquid-cooled conductor to a flexible liquid-cooled conductor having an outer flexible cooling jacket, comprising a coupling member having a tapered opening in one end portion .thereof adapted to engage with a tapered end of .the hollow conductor, means engaging the coupling member and the hollow conductor for forcing the tapered end of the hollow conductor in with axially extending openings providing com- .munication for the cooling liquid between the interior of the cooling jacket of the flexible conductor and the interior of the hollow conductor, the spline member being secured within an internal opening in the coupling member adjacent the other end thereof.

4. An electrical contact coupling for connecting a hollow liquid-cooled conductor to a flexible liquid-cooled conductor having an outer flexible cooling jacket, comprising a coupling member having a tapered opening adjacent one end portion thereof adapted to engage with a tapered end of the hollow conductor, the outer surface of the coupling member adjacent said end portion being threaded, an annular key secured to the hollow conductor, an internally threaded member provided at one end thereof with an inwardly projecting shoulder adapted to engage said key and to force the tapered end of the hollow conductor into firm contact with the tapered opening of the couplin member as the threaded member is turned about the threaded outer surface of the coupling member, and a spline member secured to the end of the flexible conductor, provided with axially extending openings providing communication for the cooling liquid between the interior of the cooling jacket of the flexible conductor and the interior of the hollow conductor, the spline member being secured within an internal opening in the coupling member adjacent the other end thereof.

5. An electrical contact coupling for connecting a hollow liquid-cooled conductor to a flexible liquid-cooled conductor having an outer flexible cooling jacket, comprising a coupling member having a tapered opening adjacent one end portion thereof adapted to engage with a tapered end of the hollov. conductor, means for holding the tapered end of the hollow conductor in firm contact within the tapered opening of the coupling member, and a spline member having a cylindrical body portion and a plurality of coaxially disposed projections spaced radially about one end of the body portion provided with axially extending openings therethrough providing communication for the cooling liquid between the interiorof the cooling jacket of the flexible ccnductor and the interior of the hollow conductor, the spline member being secured to the end of the flexible conductor and to the interior of the other end of the coupling member along the edges of the projections of the spline member in contact with the flexible conductor and with the interior of said other end of the coupling memher.

6. An electrical contact coupling for connecting a hollow liquid-cooled conductor to a flexible liquid-cooled conductor having an outer flexible cooling jacket, comprising a substantially cylindrical coupling member provided with a tapered opening adjacent one end portion thereof adapted to engage with a tapered end of the hollow conductor and provided with a plurality of openings in the cylindrical surface of the other end portion thereof, means for holding the tapered end of the hollow conductor in firm contact within the tapered opening of the coupling member, and a spline member having a cylindrical body portion and a plurality of coaxially disposed projections spaced radially about one end of the body portion so as to correspond to the positions of the openings in said other end portion of the coupling member, the spline member being positioned about one end of the flexible conductor with the projections welded to the surface of the ell flexible conductor and being positioned within said other end portion of the coupling member with the projections welded thereto adjacent the opening in said end portion of the coupling member, the spline member being provided with openings extending through the projections of the spline member longitudinally of the axis thereof and communicating between the interior of the coupling member and the interior of the outer cooling jacket of the flexible conductor.

7. An electrical contact coupling for connecting a hollow liquid-cooled conductor to a flexible liquid-cooled conductor having an outer flexible cooling jacket, comprising a substantially cylindrical coupling member having a tapered opening adjacent one end portion thereof adapted to engage with a tapered end of the hollow conductor and having a plurality of openings in the cylindrical surface of the other end portion thereof, means for holding the tapered end of the hollow conductor in firm contact within the tapered opening of the coupling member, and a spline member having a cylindrical body portion and a plurality of coaxiall disposed projections spaced radially about one end of the body portion so as to correspond to the positions of the openings in said other end portion of the coupling member with an opening extending longitudinally of the spline member tlnough the body portion and projections thereof, the spline member being positioned about one end of the flexible conductor with the projections Welded to the surface of the flexible conductor and being positioned within said other end portion of the coupling member with the projections welded thereto adjacent the openings in said end portion of the coupling member, the outer flexible cooling jacket of the flexible conductor being secured to the outer surface of the cylindrical body portion of the spline member in such manner that the longitudinal openings extending through the projections and cylindrical body portion of the spline member provide communication between the interior of the coupling member and the interior of the outer cooling jacket of the flexible conductor.

LEO H. TIMMINS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 409,181 De Ferranti Aug, 20, 1889 1,365,306 Dickinson Jan. 11, 1921 

